Life expectancy for some U.S. women falling

(WUSA 9)-- Although women still outlive men in the U.S., a new study found that the lifespan for some American women is becoming shorter. The frightening aspect of the study: some experts don't know why this is happening.

However, some experts do offer an explanation. They believe the cause is higher smoking rates, obesity and less education. The study found the main regions where women are not living as long are rural areas and the South and West.

Similarly, two years ago, a study found that women especially in the South, were experiencing shorter lifespans. In his study, Dr. Christopher Murray addressed the shorter lifespans of women in the South, which could be linked to higher rates of smoking and higher rates of women who don't finish school in some parts of the region.

AP reports, "Some also think the statistics could reflect a migration of healthier women out of rural areas, leaving behind others who are too poor and unhealthy to relocate. That would change the rate, and make life expectancy in a county look worse," explained Bob Anderson of the CDC's National Center for Health Statistics.

The latest research released by the journal, Health Affairs, found that in 43 percent of the nation's counties, women who are 75 and younger are experiencing declining lifespans. Although a girl born in the U.S. today has an average lifespan of 81 years, and a boy born in the U.S. today has an average lifespan of 76 years, men's lifespans have remained the same or even improved.

Yet some experts still cannot explain the decrease in life expectancy of some U.S. women. Furthermore, researchers cannot exactly calculate the number of women affected by the trend. A Harvard School of Public Health sociologist, Jennifer Karas Montez, estimates it at 12 percent.

But there is some positive news for women. AP reports that educated and wealthier women in the U.S. seem to be experiencing the opposite effect: an increase in life expectancy.

Late last year, the New York Times reported a study that found life expectancy is rising around the world, but mostly due to leaps in developing countries. While the World Health Organization notes the disparities in life expectancy between countries, in 2010, the average life expectancy of women worldwide rose to 70 years.

So while the Centers for Disease Control and Prevention warns that U.S. women's life expectancy is more stagnant than men's, American women are still outliving their counterparts around the world by about an average of 10 years.